Radial head replacement with adjustable stem

Abstract

Provided herein are prostheses for replacement of a proximal end of a radius bone. The prosthesis may include a head and a stem coupled to the head. The stem may be configured to fit in a bore of a radius bone. The stem may include a flexible portion, such as one or more cut outs, that allows the stem to bend. This may ease insertion of the radial head prosthesis in the radius.

Description

TITLERADIAL HEAD REPLACEMENT WITH ADJUSTABLE STEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present disclosure claims priority to U.S. Provisional Patent Application 63 / 556,562 titled “RADIAL HEAD REPLACEMENT WITH ADJUSTABLE STEM”, which was filed on February 22, 2024, and which is incorporated herein in its entirety.BACKGROUND

[0002] The head of a bone generally includes a rounded extension that is used to form a part of a joint. The head is the main articulating surface with the adjacent bone. When the head of a bone becomes fractured or otherwise damaged, it may be difficult to repair. When the head is irreparable, prosthetic replacement of the head of the bone may be necessary to keep the joint intact.

[0003] Specifically, prosthetic replacement of the radial head in the elbow joint may be performed. The elbow joint is comprised of the humerus, the radius, and the ulna. The radial head articulates at its end with the capitellum of the humerus, to form the humeroradial joint, and on its side with the radial notch of the ulna, to form the proximal radioulnar joint.

[0004] A radial head replacement may include removing the entirety of the radial head and replacing it with a radial head prosthesis. Typical radial head replacements include a stem portion and a head portion. The stem portion is used to secure the head to the radius, while the head is configured to mimic the articulating surfaces of the radial head. During replacement, a bore may be drilled into the radius bone. The stem portion of the radial head prosthesis may be configured to fit in the bore of the radius to secure the prosthesis to the radius.

[0005] Upon implantation of the radial head prosthesis, it may be difficult to maneuver the stem into a bore of the radius without interfering with the capitellum and surrounding tendons. This may result in the surgeon having to remove more bone of the radius than necessary to fit the radial head prosthesis into place. There exists a need for a radial head prosthesis that allows ease of insertion.SUMMARY

[0006] The present disclosure provides a new and innovative radial head prostheses that may be easier to insert than current solutions. The prostheses provided herein may allow a surgeon to implant a radial head prosthesis without having to remove unnecessary bone from the radius. The prostheses according to the present disclosure may include a monoblock design where the head is directly coupled to the stem, or the prostheses may include a modular design where the head is indirectly coupled to the stem, such as through use of a trunnion.

[0007] One aspect of the present disclosure provides a radial head prosthesis including a stem with a flexible portion that allows the stem to bend or flex. Another aspect of the present disclosure provides a radial head replacement including a stem with two portions moveable with respect to each other. The two portions may be coupled together through a pivot support. Yet another aspect of the present disclosure provides a radial head replacement including a stem and a trunnion moveable with respect to each other.

[0008] Yet another aspect of the present disclosure provides a prosthesis that includes a modular design with an integrated screw configured to secure a head of the prosthesis to the trunnion. The integrated screw may prevent screw back out once the prosthesis is implanted in the elbow joint, which is a common problem among modular designs.

[0009] Additional features and advantages of the disclosed methods are described in, and will be apparent from, the following Detailed Description and the Figures.BRIEF DESCRIPTION OF THE FIGURES

[0010] Figs. 1A and IB illustrate a prosthesis for replacement of a proximal end of a radius bone according to an example of the present disclosure.

[0011] Fig. 2A illustrates the prosthesis of Figs. 1A and IB including a dovetail flexible portion according to an example of the present disclosure. Fig. 2B illustrates a closer view of the dovetail cuts of Fig. 2A.

[0012] Fig. 3 illustrates the prosthesis of Figs. 1 A and IB being implanted into a radius bone.

[0013] Fig. 4 illustrates a prosthesis for replacement of a proximal end of a radius bone according to an example of the present disclosure.

[0014] Fig. 5 illustrates an exploded view of the prosthesis for replacement of a proximal end of a radius bone as shown in Fig. 4.

[0015] Fig. 6 illustrates the prosthesis of Figs. 4 and 5 being implanted into a radius bone.

[0016] Figs. 7 and 8 illustrate a prosthesis for replacement of a proximal end of a radius bone according to an example of the present disclosure.

[0017] Figs. 9-11 illustrate a prosthesis for replacement of a proximal end of a radius bone with a screw retained in a trunnion of the prosthesis according to an example of the present disclosure.

[0018] Figs. 12 and 13 illustrate a prosthesis for replacement of a proximal end of a radius bone with a screw retained in a head of the prosthesis according to an example of the present disclosure.

[0019] Fig. 14 illustrates the prosthesis of Figs. 12-13 being implanted into a radius bone.

[0020] Figs. 15 A, 15B, and 16 illustrate a prosthesis for replacement of a proximal end of a radius bone according to an example of the present disclosure.

[0021] Figs. 17-19B illustrate a prosthesis for replacement of a proximal end of a radius bone according to an example of the present disclosure.DETAILED DESCRIPTION OF EXAMPLES

[0022] The present disclosure is directed to a prosthesis for a proximal end of a radius bone that allows ease of insertion into a bore of a radius bone.

[0023] Figs. 1 A and IB show a prosthesis 100 for replacement of a proximal end of a radius bone according to an example of the present disclosure. Referring to Fig. 1 A, the prosthesis 100 may include a head 110 and a stem 120. A first end portion 122 of the stem 120 may be coupled to the head 110. In some examples, when coupled to the first end portion 122 of the stem 120, the head 110 may be orthogonal to the stem 120. In other examples, the head 110 may be tilted relative to a central axis of the first end portion 122 of the stem 120.

[0024] In some examples, the prosthesis 100 may have a monoblock design where the first end portion 122 of the stem 120 may be directly coupled to or formed integrally with a bottom surface 112 of the head 110. In other examples, the prosthesis may have a modular design where the first end portion 122 of the stem 120 may be indirectly coupled to the head 110, such as by use of a trunnion. As will be described inmore detail herein, the first end portion 122 of the stem 120 may be directly coupled to the trunnion, and the trunnion may be configured to receive the head 110. This may allow the head 120 to be removably coupled to the stem 120 and / or the trunnion.

[0025] The head 110 may be configured to mimic the head of a radius bone. For example, the head 110 may be (substantially) cylindrical in shape and may include a top surface 114 (opposite the bottom surface 112) configured to engage with a capitellum of the humerus bone to form the elbow joint. Additionally or alternatively, the head 110 may include a side surface configured to engage with a radial notch of the ulna.

[0026] The stem 120 may include an elongated shaft configured to be received in a bore of the radius bone to secure the prosthesis to the radius. In some examples, the stem 120 may be (substantially) cylindrical or have any desired shape. The stem 120 may include a second end portion 124, opposite the first end portion 122. The second end portion 124 may be configured to guide the stem 120 into the bore of the radius bone. The second end portion 124 may include a taper, a semi-spherical shape, a sloped surface, and / or any suitable geometry for guiding the stem 120 into the radius bone.

[0027] The stem 120 may be comprised of any suitable material, such as biocompatible materials (metal alloys (titanium alloys, cobalt chromium alloys, stainless steel, etc.), composite materials, plastics (polyethylene, among others), ceramics, and / or the like), and / or bioabsorbable materials (polygly colicacid (PGA), polylactic acid (PLA), copolymers thereof, etc.), among others. In some examples, the stem may be made of a substantially rigid material so that the prosthesis is secured in the bore of the radius bone without substantial movement.

[0028] The first end portion 122 of the stem 120 may define a first central axis 101. In some examples, the stem 120 may include a flexible portion 126 that allows the stem 120 to bend or “flex” such that the second end portion 124 is offset from the first central axis 101 by an angle relative to a second central axis 102 of the second end portion 124. In some examples, the maximum angle between the first central axis 101 and the second central axis 102 may be in a range of about 0 degrees to about (+ / -) 90 degrees, for example, in a range of about 0 degrees to about (+ / -) 65 degrees, about 0 degrees to about (+ / -) 55 degrees, about 0 degrees to about (+ / -) 45 degrees, or about 0 degrees to about (+ / -) 35 degrees, about 0 degrees to about (+ / -) 25 degrees, or about 0 degrees to about (+ / -) 15 degrees.

[0029] In some examples, the flexible portion 126 may be formed along a portion of the stem 120. In some examples, the flexible portion 126 may make up about 10% toabout 90% of the stem 120 along its length, such as about 10% to about 20%, about 20% to about 30%, about 30% to about 40%, about 40% to about 50%, about 50% to about 60%, about 60% to about 70%, or about 70% to about 80%, or about 80% to about 90% of the length of the stem 120. In other examples, the flexible portion 126 may be formed along the whole length of the stem 120.

[0030] As seen in Fig. IB, the stem may have a length, X (including Li, L2, and L3), along the longitudinal axis of the stem when the stem is in a non-bending configuration. The first end portion 122 may have a length Li along the longitudinal axis. The second end portion 124 may have a length L3 along the longitudinal axis. The flexible portion 126 may be disposed between the first end portion 122 and the second end portion 124, and the flexible portion 126 may have a length L2 along the longitudinal axis.

[0031] In some embodiments, the length Li of the first portion 122 forms about 10-30% of length X, such as 10-15%, 15-20%, 20-25%, or 25-30%. In some embodiments, the length L3 of the second portion 124 forms about 10-30% of length X, such as 10-15%, 15-20%, 20-25%, or 25-30%. In some embodiments, the length L2 of the flexible portion 126 forms about 10-90% of the total length X, such as 10-20%, 20- 30%, 30-40%, 40-50%, 50-60%, 60-70%, 70-80%, or 80-90%.

[0032] In some examples, the flexible portion 126 includes a first end 126a proximal to the head 110 and a second end 126b opposite the first end 126a. The stem 120 may include a first end 122a proximal to the head 110. In some examples, the distance Di from the first end 122a of the stem 120 to the first end 126a of the flexible portion 126 may be in a range of about 0.1 X to about 0.45 X and the distance D2 from the first end 122a of the stem 120 to the second end 126b of the flexible portion 126 may be in a range of about 0.55 X to about 0.9 X.

[0033] In some examples, the stem 120 may include one or more solid portions 128a, 128b on either side or both sides of the flexible portion 126. By solid portions, it may be meant a portion that is not able to bend or “flex”. In some examples, the one or more solid portions 128a, 128b may be proximal and / or distal to the flexible portion 126. In some examples, the interface between the head 110 (and / or the trunnion) and the stem 120 may include a solid portion 128a to provide support to the head after insertion.

[0034] In some examples, the flexible portion 126 may include one or more cuts or cutouts that allow an otherwise rigid material to bend or “flex”. In some examples,the one or more cuts may traverse the entire diameter or a partial diameter of the stem 120.

[0035] In some examples, the flexible portion 126, the entire length of the stem 120, and / or a portion of the stem 120 may include a cannulation through the central axis of the stem 120. The one or more cuts or cutouts may extend from the outside surface of the stem 120 through the inside surface of the cannulation.

[0036] As depicted in Figs. 1 A and IB, the one or more cutouts may include one or more helical cuts, such as one (two, three, four...) continuous helical cut(s), around the flexible portion 126 of the stem 120. For example, the helical cut may extend circumferentially around the stem at least a plurality of times and along a length of the stem 120 to make up the flexible portion 126. The helical cut may create a helical spring like mechanism allowing the flexible portion 126 to bend or flex in response to forces acted upon it, but returning to its original state at rest.

[0037] It can be appreciated that other laser cutting techniques may be used to impart a flexible quality to a portion of the stem 120. For example, the helical cut may include a straight helical cut or the helical cut may include a series of patterns (such as dove tail cuts, sinusoidal patterns, etc.) along the helical path. The dimensions of the pattern may be optimized to provide the stem with enough flexibility to allow ease of insertion, but enough rigidity to allow stabilization after implantation.

[0038] As depicted in Figs. 2A and 2B, in some examples, the one or more cuts may include one or a plurality of dovetail cuts 134 surrounding a partial or a full circumference of the stem 120. A series of circumferential dovetail cuts 136a, 136b, 136c may be placed around a full or a partial circumference of the stem 120 along the length of the stem 120. In some examples, the series of circumferential dovetail cuts 136a, 136b, 136c are perpendicular to the first central axis 101 when the stem 120 is in the non-bending configuration. In some examples, the series of circumferential dovetail cuts 136a, 136b, 136c are non-perpendicular to the first central axis 101 when the stem 120 is in the non-bending configuration.

[0039] Referring to Fig. 2B, in some examples, the series of circumferential cuts 136a, 136b, 136c are spaced apart along the length of the stem by distance D4. In some examples, the distance D4 between circumferential dovetail cuts is uniform, such as the same between 136a and 136b and between 136b and 136c. In some examples, the distance D4 between circumferential dovetail cuts is non-uniform, such as different between 136a and 136b and between 136b and 136c. In some examples, D4 is betweenabout 3.5 mm and about 10 mm apart along the length of the stem. In some examples, the series of circumferential cuts 136a, 136b, 136c have a thickness Ti in a range of about 2 mm to about 4 mm.

[0040] Still referring to Fig. 2B, each dovetail 134 may include a portion with a larger width Wi and a portion with a narrower width W2. In some examples, the larger width Wi of the dovetail 134 is between about 3 mm and about 6 mm and the smaller width W2 of the dovetail 134 is between 1 mm and 3 mm. The dovetails 134 in the series of circumferential dovetail cuts 136a, 136b, 136c may be along a longitudinal axis 103 parallel to the first central axis 101. In some examples, the dovetails 134 of the series of circumferential dovetail cuts 136a, 136b, 136c may be along an axis transverse to the first central axis 101.

[0041] Fig. 3 illustrates an implantation of the prosthesis 100 into the radius bone. As can be seen from Fig. 3, the flexible portion 126 of the stem 120 may allow a surgeon to shoehorn the prosthesis 100 into the bore in the radius. The flexibility allows for ease of insertion. However, once inserted, the bore in the radius bone may align the first central axis with the second central axis and prevent substantial movement of the flexible portion 126of the prosthesis 100 after implantation.

[0042] Figs. 4 and 5 show a prosthesis 200 for replacement of a proximal end of a radius bone according to an example of the present disclosure. The prosthesis 200 may include a head 210 and a stem 220. The head 210 of prosthesis 200 may be the same as the head 110 of prosthesis 100. In some examples, the stem 220 of prosthesis 200 may be combined with any of the embodiments of stem 120 of prosthesis 100.

[0043] A first portion 222 of the stem 220 may be coupled to the head 210. When coupled to the first portion 222 of the stem 220, the head 210 may be orthogonal to the stem 220 or the head 210 may be tilted relative to a central axis of the first portion 222 of the stem 220.

[0044] In some examples, the prosthesis 200 may have a monoblock design where the first portion 222 of the stem 220 may be directly coupled to or formed integrally with a bottom surface 212 of the head 210. In some examples, the prosthesis may have a modular design where the first portion 222 of the stem 220 may be indirectly coupled to the head 210, such as by use of a trunnion. As will be described in more detail herein, the first portion 222 of the stem 220 may be directly coupled to or integral withthe trunnion, and the trunnion may be configured to receive the head 210. This allows the head 210 to be removably coupled to the stem 220 and / or the trunnion.

[0045] The stem 220 may include an elongated shaft configured to be received in a bore of the radius bone to secure the prosthesis to the radius. The stem 220 may include a first portion 222 and a second portion 224. The first portion 222 and the second portion 224 may be moveable with respect to each other. In some examples, the second portion 224 may be moveable with respect to the first portion 222 (and vice versa) on at least one rotation axis (i.e. one rotation axis, two rotation axes, three rotation axes. . .).

[0046] In some examples, the first portion 222 and the second portion 224 are coupled together via a pivot support 230. In some examples, the pivot support 230 may include a hinge, a pin, a ball and socket interface, or any other suitable pivot support 230. In the depicted embodiment, the first portion 222 and the second portion 224 are coupled together using a pin 230. The first portion 222 and / or the second portion 224 of the stem 220 may have at least one rotation axis about the pivot support 230.

[0047] In some examples, the first portion 222 of the stem 220 may define a first central axis 201 and the second portion 224 of the stem 220 may define a second central axis 202. In some examples, the maximum angle between the first central axis and the second central axis may be in a range of about 0 degrees to about (+ / -) 90 degrees, for example, in a range of about 0 degrees to about (+ / -) 65 degrees, about 0 degrees to about (+ / -) 55 degrees, about 0 degrees to about (+ / -) 45 degrees, or about 0 degrees to about (+ / -) 35 degrees, about 0 degrees to about (+ / -) 25 degrees, or about 0 degrees to about (+ / -) 15 degrees.

[0048] The second portion 224 of the stem 220 may include a first end portion 226 proximal to the first portion 222 of the stem 220 and a second end portion 228 distal to the first portion 222. The first end portion 226 may include one or more stop surfaces 226a, 226b that limit the range of motion of the second portion 224 in relation to the first portion 222. In some examples, the stop surface 226a, 226b may include an angled surface relative to the second central axis that permits and / or limits the range of motion of the second portion 224 relative to the first portion 222. In some examples, the smaller the angle of the stop surface 226a, 226b in relation to the second central axis where the angle of the stop surface 226a, 226b is less than 90 degrees, the larger the rotation angle of the second portion 224 is relative to the first portion 222.

[0049] In some examples, the first portion 222 may include a first end portion 240 and a second end portion 242. The first end portion 240 may be coupled, directly orindirectly, to the head 210 and / or a trunnion. As can be seen in Figs. 4 and 5, in some examples, the second end portion 242 of the first portion 222 may include one or more stop surfaces 242a, 242b that limit the range of motion of the first portion 222 in relation to the second portion 224. In some examples, the stop surface 242a, 242b includes an angled surface relative to the first central axis that permits and / or limits the range of motion of the first portion 222 relative to the second portion 224. In some examples, the smaller the angle of the stop surface 242a, 242b in relation to the first axis, the larger the rotation angle of the first portion 222 is relative to the second portion 224.

[0050] Referring back to Fig. 4, the first end portion 226 of the second portion 224 of the stem 220 may overlap the second end portion 242 of the first portion 222 of the stem 220 when viewed from an axis perpendicular to the first central axis 201 and / or the second central axis 202. The pivot support 230, such as a pin, may be positioned in the overlapping region to restrict rotation of the first portion 222 and / or the second portion 224 relative to each other in the direction of the overlap.

[0051] Fig. 6 shows a prosthesis 200 according to an example of the present disclosure being inserted into a bore in a radius bone. As can be seen in the figure, the hinge mechanism allows a surgeon to shoehorn the prosthesis 200 into the bore of the radius bone. As used herein, shoehoming may refer to an act of making the radial head prosthesis 200 to fit in the bore of the radial canal. However, once inserted, the walls of the bore may cause the first central axis 201 to align with the second central axis 202 and may restrict rotation of the first portion 222 and the second portion 224, holding the prosthesis 200 into place.

[0052] Figs. 7 and 8 show a prosthesis 300 for replacement of a proximal end of a radius bone according to an example of the present disclosure. The prosthesis 300 may include a head 310 and a stem 320. In some examples, the prosthesis 300 may also include a cylindrical protrusion used as a mounting point for the head 310, also known as a trunnion 330. It can be appreciated that while the trunnion 330 is depicted as cylindrical, the trunnion 330 may be any suitable shape to interface with the head 310. The head 310 may include a recess, such as in the bottom surface or a side surface, configured to receive the trunnion 330 and secure the head 310 to the prosthesis 300.

[0053] The stem 320 may include an elongated shaft configured to be received in a bore of the radius bone to secure the prosthesis 300 to the radius. In some examples, the stem 320 may be (substantially) cylindrical or have any desired shape. The stem may include a first end portion 322 and a second end portion 324 opposite the first end portion322 and configured to guide the stem 320 into the bore of the radius bone. The second end portion 324 may include a taper, a semi-spherical shape, a sloped surface, and / or any suitable geometry for guiding the stem 320 into the radius bone.

[0054] The first end portion 322 of the stem 320 may be disposed between the trunnion 330 / the head 310 and the second end portion 324. The stem 320 and the trunnion 330 and / or the head 310 may be moveable with respect to each other, as depicted in Fig. 7. In some examples, the trunnion 330 / head 310 and the stem 320 may include one or more features that couple with each other and allow the trunnion 330 / head 310 to move or pivot with respect to the stem 320.

[0055] In some examples, the stem 320 includes a main stem body and a peg 340 protruding from a side surface of the main stem body. The peg 340 may have any suitable shape, such as a rounded shape. In some examples, the peg 340 protrudes from the main stem body substantially perpendicular to a surface (and / or a central axis) of the main stem body. In some examples, the peg 340 protrudes from the main stem body at a nonperpendicular angle to a surface (and / or a central axis) of the main stem body.

[0056] The trunnion 330 may include a pivot hinge connector 350 protruding from an outside surface of the trunnion 330. In some examples, the pivot hinge connector 350 protrudes from a bottom surface, a top surface, or a side surface of the trunnion 330. In some examples, the pivot hinge connector 350 defines an elongated slot 350a, such as an elongated slot 350a with rounded edges. The elongated slot 350a may be configured to receive the peg 340 of the stem 320.

[0057] In some examples, when the peg 340 is received in the elongated slot 350a, the trunnion 330 may be configured to move about the peg 340 by at least one rotation axis. In some examples, the trunnion 330 is configured to move with respect to the stem 320 about a central axis of the stem 320 and along a central axis of the elongated slot 350a. Additionally or alternatively, the trunnion 330 may be configured to pivot about the peg 340 along a rotational axis of the peg 340.

[0058] The trunnion 330 and the stem 320 may include one or more features configured to mate with each other to secure the trunnion 330 onto the stem 320 after insertion. While it may be advantageous to move the head 310 and / or the trunnion 330 with respect to the stem 320 for ease of insertion, it may be important that the trunnion 330 and / or the head 310 remain stationary after implantation.

[0059] In some examples, one of the trunnion 330 or the stem 320 may include a stepped portion 360. For example, the stepped portion 360 may include a cylinder, arectangular prism, a conical shape, or any suitable shape with a smaller diameter / width than the largest width of the trunnion 330 or the stem 320. The stem 320 or the trunnion 330 may include a recess complimentary to the stepped portion 360 and configured to mate with the stepped portion 360.

[0060] The peg 340 may be configured to translate along the elongated slot 350a of the pivot hinge connector 350 so as to translate the trunnion 330 closer to and farther away from the stem 320 along a central axis of the elongated slot 350a.

[0061] It can be appreciated that the head 310 may be integral with the trunnion 330 or the head 310 may replace the trunnion 330 entirely. If the trunnion 330 is not present, the head 310 may move with respect to the stem 320 as described between the trunnion 330 and the stem 320.

[0062] Figs. 9-11 show yet another embodiment of a prosthesis 400 for replacement of a proximal end of a radius bone according to an example of the present disclosure. The prosthesis 400 may be used in combination with any other embodiment of prosthesis (100, 200, 300) disclosed herein.

[0063] The prosthesis 400 may include a modular head 410, a stem 420, and a trunnion 430 coupled to the stem 420. The trunnion 430 may be configured to receive the head 410. As shown in Fig. 9, the head 410 may include a recess 412, such as in a side surface of the head 410, configured to interface with the trunnion 430. For example, the recess 412 of the head 410 and the outside surface of the trunnion 430 may have complimentary or partially complimentary shapes. In some examples, the recess 412 is on a bottom surface of the head 410.

[0064] In the depicted embodiment, the head 410 is configured to slide onto the trunnion 430 from the side (i.e. the head 410 is side loading). The trunnion 430 may include a screw 432 with threads retained in a central cavity of the trunnion 340 configured to secure the head 410 onto the trunnion 430. As shown in Fig. 10B, the screw 432 may be configured to rotate along a shaft 436 in the internal cavity 434 of the trunnion 430. A screw head 432a of the screw 432 may be accessible from an outside surface of the trunnion 430. In some examples, the trunnion 430 may include a pin configured to hold the screw 432 to prevent axial movement of the screw 432, which may prevent the screw 432 from backing out of the trunnion 430.

[0065] As shown in Fig. 10A, the head 410 may include an internal cavity 414 in communication with the recess 412. The internal cavity 414 may be separated into at least two portions: a first portion 416 with a diameter larger than the major diameter ofthe screw closest to the opening of the recess 412 and a second portion 418 configured to receive the threads of the screw 432. This allows the head 410 to initially be slid onto the trunnion 430 without interfacing the threads of the screw 432 as illustrated in Fig. 11.

[0066] The head 410 may include another cavity 422 extending from the recess 412 to the outside surface configured to allow access to the screw head 432a of the screw 432 exposed on an outer surface of the trunnion 430 when the head 410 is (partially) received by the trunnion 430. Upon insertion of the head 410 onto the trunnion 430, a user may rotate the screw head 432a (using a driver), causing the screw 432 to advance into the complimentary cavity 418 of the head 410, translating the head 410 along a central axis of the screw 432 and trunnion 430 until the head 410 and the trunnion are secured together.

[0067] As shown in Fig. 11, the trunnion 430 may include one or more wings 450 extending from an outside surface of the trunnion 430, such as a top surface, a bottom surface, or a side surface. The wings 450 may include a taper along the length of the wing 450. The recess 412 of the head 410 may be configured to receive the wing 450. The largest width of the wing 450 may be substantially the same as a width of the recess 412 configured to receive the wing 450. As the head 410 is translated along the trunnion 430, the wing 450 may translate along the recess 412 until the largest width of the wing 450 interfaces the recess 412. The taper of the wing 450 may act to lock trunnion 430 onto the head 410, such as through a friction fit.

[0068] Fig. 12 depicts an embodiment of prosthesis 400 with a head 410 and a trunnion 430 with the screw 432 retained within a central cavity 414 of the head 410 as opposed to being retained within the trunnion 430. Fig. 13 is a bottom up view of the head 410 of Fig. 12. In this depicted embodiment, the trunnion 430 includes a cavity 434 that may be separated into at least two portions: a first portion 434a with a diameter larger than the major diameter of the screw 432 and a second portion 434b configured to receive the threads of the screw 432.

[0069] In the depicted embodiment, the screw 432 may include a recess 432b, such as between the threads and the screw head 432a of the screw 432. A pin 440 in the head 430 may interface with the recess 432b in the screw 432 preventing axial movement of the screw 432. The use of the pin 440 may prevent the screw 432 from backing outof the internal cavity 414 of the head 410, which could cause the head 410 to detach or move relative to the trunnion 430 and / or the stem 420.

[0070] Fig. 14 shows a prosthesis 400 according to an example of the present disclosure being inserted into a bore in a radius bone. As can be seen in Fig. 14, prosthesis 400 allows the head 410 to be translated and secured onto the trunnion 430 after the stem 420 and the trunnion 430 are secured to the radius.

[0071] Figs. 15 A, 15B, and 16 depict a prosthesis 500 for replacement of a proximal end of a radius bone according to an example of the present disclosure. Prosthesis 500 may be used in combination with any other embodiments disclosed herein.

[0072] Prosthesis 500 may include a head, a trunnion 530, and a stem 520. The trunnion 530 may include a cavity 512 configured to receive an end portion of the stem 520. A spring or other biasing mechanism 540 may be coupled to the cavity 512 of the trunnion 530, where the spring or other biasing mechanism may be enclosed between the end portion of the stem 520 and the internal cavity 512 of the trunnion 530. The spring 540 may be compressed by downward motion of the trunnion 530 with respect to the stem 520. Upon compression of the spring 540, the trunnion 530 may be “locked” to the stem 520, keeping the spring 540 in a compressed configuration and shortening the total length of the prosthesis 500. This configuration may be advantageous for insertion of the prosthesis 500 into the bore of the radius bone. The smaller length of the prosthesis 500 may result in less interference with the capitellum and surrounding tendons upon insertion.

[0073] Upon implantation of the prosthesis 500 into the bore of the radius, the trunnion 530 and / or head may be “unlocked” from the stem 520, allowing the spring 540 to bias the trunnion 530 and / or head upward relative to the stem 520. This may allow the head to interface with the capitellum.

[0074] In some examples, the cavity 512 of the trunnion may include one or more threads 525 configured to interface with one or more threads of the end portion of the stem 520. A downward force and rotation of the trunnion 530 and / or the stem 520 with respect to each other may act to lock the stem 520 to the trunnion 530 with the spring 540 in the compressed position as depicted in Fig. 15 A. Upon opposite rotation of the trunnion 530 and / or stem 520 with respect to each other, the parts may unlock allowing the spring component 540 to bias the trunnion 530 upward as depicted in Fig. 15B.

[0075] Additionally or alternatively, as illustrated in Fig. 16, the trunnion 530 may include a peg 550 configured to mate with a track 560 on an outside surface of the stem 520. The track 560 may include a first path 560a parallel to a central axis of the stem 520 and a second path 560b configured to lock the trunnion 530 to the stem 520 in a compressed state. In some examples, the second path 560b is perpendicular to or at an acute angle to the first path 560a. It can be appreciated that other configurations of a track 560 may be used to prevent axial movement of the trunnion 530 relative to the stem 520, locking the spring component 540 in a compressed state.

[0076] Figs. 17-19B show yet another embodiment of a prosthesis 600 for replacement of a proximal end of a radius bone according to an example of the present disclosure. The prosthesis 600 may be used in combination with any other embodiment of prosthesis (100, 200, 300, 400, 500) disclosed herein.

[0077] The prosthesis 600 may include a modular head 610, a stem 620, and a trunnion 630 coupled to the stem 620. The trunnion 630 may be configured to receive the head 610. The trunnion 630 may include a base portion 630a and biased portion 630b. The base portion 630a may be configured to contact at least a portion of the bottom surface of the head 610.

[0078] As shown in Fig. 17, the head 610 may include a recess 612, such as in a side surface of the head 610, configured to interface with the biased portion 630b of the trunnion 630. For example, the recess 612 of the head 610 and the outside surface of a biased portion 630b of the trunnion 630 may have complimentary or partially complimentary shapes. In some examples, the recess 612 is on a bottom surface of the head 610. In some examples, the recess 612 extends from one side surface of the head 610 to another side surface of the head 610.

[0079] In the depicted embodiment, the head 610 is configured to slide onto the biased portion 630b of the trunnion 630 from the side (i.e. the head 610 is side loading). While sliding the head 610 on the trunnion 630, the biased portion 630b of the trunnion 630 may be in a relaxed state as shown in Figs. 17 and 18. For example, in the relaxed state, a spring may act to bias the biased portion 630b away from the base portion 630a of the trunnion 630. As can be seen in Fig. 19B, the spring may be located in an internal cavity 632 of the base portion 630a of the trunnion 630.

[0080] After the head 610 is on the trunnion 630, the rotation position of the head 610 may be adjusted. Once the head 610 is on the trunnion 630, the head 610 may be locked to the trunnion 630 by transitioning the biased portion 630a of the trunnion 630from a relaxed configuration to a stressed configuration as shown in Figs. 19A and 19B. In some examples, the biased portion 630b is pushed down toward the base portion 630a compressing the spring to the base portion, such as with a tool. The biased portion may be locked into place in the stressed configuration. When the biased portion 630b is in the locked, stressed configuration, the outside surface of the biased portion 630b may interact with the inside surface of the recess 612 to secure the head 610 to the trunnion 630.

[0081] Without further elaboration, it is believed that one skilled in the art can use the preceding description to utilize the claimed inventions to their fullest extent. The examples and aspects disclosed herein are to be construed as merely illustrative and not a limitation of the scope of the present disclosure in any way. It will be apparent to those having skill in the art that changes may be made to the details of the above-described examples without departing from the underlying principles discussed. In other words, various modifications and improvements of the examples specifically disclosed in the description above are within the scope of the appended claims. For instance, any suitable combination of features of the various examples described is contemplated.EMBODIMENTS

[0082] Various aspects of the subject matter described herein are set out in the following numbered embodiments:

[0083] Embodiment 1. A prosthesis for replacement of a proximal end of a radius bone comprising: a head; and a stem configured to be received in a bore of a radius bone, wherein an end portion of the stem is coupled to the head, and wherein the stem comprises a flexible portion, wherein the flexible portion comprises one or more cuts that allow the stem to bend.

[0084] Embodiment 2. The prosthesis of embodiment 1, wherein the flexible portion comprises a cannulation.

[0085] Embodiment 3. The prosthesis of embodiment 2, wherein the flexible portion comprises an outside surface and an inside surface that defines the cannulation,and wherein the one or more cuts transverse the flexible portion from the outside surface to the inside surface.

[0086] Embodiment 4. The prosthesis of any one of embodiments 1-3, wherein the stem further comprises one or more solid portions on either side or both sides of the flexible portion.

[0087] Embodiment 5. The prosthesis of embodiment 4, wherein the one or more solid portions is proximal to the flexible portion.

[0088] Embodiment 6. The prosthesis of any one of embodiments 1-5, wherein the one or more cuts comprise one continuous cut.

[0089] Embodiment 7. The prosthesis of embodiment 6, wherein the one or more cuts comprise one continuous cut.

[0090] Embodiment 8. The prosthesis of any one of embodiments 1-7, wherein the one continuous cut comprises a helical cut.

[0091] Embodiment 9. The prosthesis of any one of embodiments 1-8, wherein the stem is cannulated along an entire length of the stem.

[0092] Embodiment 10. The prosthesis of any one of embodiments 1-9, wherein the head is formed integrally with the end portion of the stem.

[0093] Embodiment 11. The prosthesis of any one of embodiments 1-10, wherein the head is formed integrally with the end portion of the stem.

[0094] Embodiment 12. A prosthesis for replacement of a proximal end of a radius bone comprising: a head; and a stem configured to be received in a bore of the radius bone, wherein the stem comprises: a first portion; and a second portion, wherein the first portion of the stem is disposed between the head and the second portion of the stem, and wherein the first portion of the stem and the second portion of the stem are moveable with respect to each other.

[0095] Embodiment 13. The prosthesis of embodiment 12, wherein the first portion of the stem and the second portion of the stem are moveable with respect to each other along at least one rotation axis.

[0096] Embodiment 14. The prosthesis of any one of embodiments 12-13, wherein the first portion of the stem and the second portion of the stem are coupled together with a pivot support, wherein the first portion of the stem and / or the second portion of the stem have at least one rotation axis about the pivot support.

[0097] Embodiment 15. The prosthesis of any one of embodiments 12-14, wherein the second portion of the stem comprises a first end portion proximal to the firstportion of the stem and a second end portion distal from the first portion of the stem, wherein the first end portion comprises a stop surface that restricts motion of the second portion of the stem with respect to the first portion of the stem.

[0098] Embodiment 16. The prosthesis of embodiment 15, wherein the first portion of the stem defines a first central axis, and the second portion of the stem defines a second central axis, wherein a maximum angle between the first central axis and the second central axis is in a range of about 0 degrees to about 90 degrees.

[0099] Embodiment 17. The prosthesis of embodiment 16, wherein the first end portion of the second portion of the stem overlaps an end portion of the first portion of the stem when viewed from an axis perpendicular to the first central axis and the second central axis.

[0100] Embodiment 18. The prosthesis of any one of embodiments 12-17, wherein the head is formed integrally with the first portion of the stem.

[0101] Embodiment 19. The prosthesis of any one of embodiments 12-18, wherein the head is removably coupled to the first portion of the stem.

[0102] Embodiment 20. A prosthesis for replacement of a proximal end of a radius bone comprising: a trunnion; and a stem configured to be received in a bore of the radius bone, wherein the stem comprises a first end portion and a second end portion, wherein the first end portion is disposed between the trunnion and the second end portion, and wherein the trunnion is moveable with respect to the stem.

[0103] Embodiment 21. The prosthesis of embodiment 20, wherein the stem comprises: a main stem body; and a peg protruding from a side surface of the main stem body, wherein the trunnion comprises a pivot hinge connector protruding from a bottom surface of the trunnion, wherein the pivot hinge connector has an elongated slot configured to receive the peg of the stem, wherein the trunnion is configured to rotate about the peg of the stem.

[0104] Embodiment 22. The prosthesis of embodiment 21, wherein the trunnion comprises a stepped portion disposed at a bottom portion of the trunnion, wherein a top portion of the main stem body comprises an opening configured to receive the stepped portion of the trunnion, wherein the peg of the stem is configured to translate along thelength of the elongated slot to move the stepped portion to and away from the opening of the stem.

[0105] Embodiment 23. The prosthesis of any one of embodiments 19-22, further comprising a head, and wherein the trunnion is configured to receive the head.

[0106] Embodiment 24. The prosthesis of embodiment 21, wherein the head is formed integrally with the trunnion.

[0107] As used herein, “about,” “approximately,” and “substantially” are understood to refer to numbers in a range of numerals, for example the range of -10% to +10% of the referenced number, preferably -5% to +5% of the referenced number, more preferably -1% to +1% of the referenced number, most preferably -0.1% to +0.1% of the referenced number. Moreover, these numerical ranges should be construed as providing support for a claim directed to any number or subset of numbers in that range. For example, a disclosure of from 1 to 10 should be construed as supporting a range of from 1 to 8, from 3 to 7, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, and so forth.

[0108] Reference throughout the specification to “various aspects,” “some aspects,” “some examples,” “other examples,” “some cases,” or “one aspect” means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one example. Thus, appearances of the phrases “in various aspects,” “in some aspects,” “certain embodiments,” “some examples,” “other examples,” “certain other embodiments,” “some cases,” or “in one aspect” in places throughout the specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures, or characteristics illustrated or described in connection with one example may be combined, in whole or in part, with features, structures, or characteristics of one or more other aspects without limitation.

[0109] When the position relation between two parts is described using the terms such as “on,” “above,” “below,” “under,” and “next,” one or more parts may be positioned between the two parts unless the terms are used with the term “immediately” or “directly.” Similarly, as used herein, the terms “attachable,” “attached,” “connectable,” “connected,” or any similar terms may include directly or indirectly attachable, directly or indirectly attached, directly or indirectly connectable, and directly or indirectly connected.

[0110] It is to be understood that at least some of the figures and descriptions herein have been simplified to illustrate elements that are relevant for a clear understanding of the disclosure, while eliminating, for purposes of clarity, otherelements. Those of ordinary skill in the art will recognize, however, that these and other elements may be desirable. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the disclosure, a discussion of such elements is not provided herein.

[0111] The terminology used herein is intended to describe particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless otherwise indicated. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term “at least one of X or Y” or “at least one of X and Y” should be interpreted as X or Y, or X and Y.

[0112] Additionally, in describing the components of the system of the present disclosure, there may be terms used like first, second, third, and fourth. These terms may be used for the purpose of differentiating one component from the other, but not to imply or suggest the substances, order, sequence, or number of the components.

[0113] It should be understood that various changes and modifications to the examples described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

Claims

CLAIMSThe invention is claimed as follows:

1. A prosthesis for replacement of a proximal end of a radius bone comprising: a head; and a stem configured to be received in a bore of a radius bone, wherein an end portion of the stem is coupled to the head, and wherein the stem comprises a flexible portion, wherein the flexible portion comprises one or more cuts that allow the stem to bend.

2. The prosthesis of claim 1, wherein the flexible portion comprises a cannulation.

3. The prosthesis of claim 2, wherein the flexible portion comprises an outside surface and an inside surface that defines the cannulation, and wherein the one or more cuts transverse the flexible portion from the outside surface to the inside surface.

4. The radial head of claim 1, wherein the stem further comprises one or more solid portions on either side or both sides of the flexible portion.

5. The radial head of claim 4, wherein the one or more solid portions is proximal to the flexible portion.

6. The prosthesis of claim 1, wherein the one or more cuts comprise one continuous cut.

7. The radial head of claim 6, wherein the one continuous cut comprises a helical cut.

8. The radial head of claim 1, wherein the one or more cuts comprise dovetail cuts.

9. The radial head of claim 1, wherein the stem is cannulated along an entire length of the stem.

10. The radial head of claim 1, wherein the head is formed integrally with the end portion of the stem.

11. The radial head of claim 1, wherein the head is removably coupled to the stem.

12. A prosthesis for replacement of a proximal end of a radius bone comprising: a head; and a stem configured to be received in a bore of the radius bone, wherein the stem comprises: a first portion; and a second portion, wherein the first portion of the stem is disposed between the head and the second portion of the stem, and wherein the first portion of the stem and the second portion of the stem are moveable with respect to each other.

13. The prosthesis of claim 12, wherein the first portion of the stem and the second portion of the stem are moveable with respect to each other along at least one rotation axis.

14. The prosthesis of claim 12, wherein the first portion of the stem and the second portion of the stem are coupled together with a pivot support, wherein the first portion of the stem and / or the second portion of the stem have at least one rotation axis about the pivot support.

15. The prosthesis of claim 12, wherein the second portion of the stem comprises a first end portion proximal to the first portion of the stem and a second end portion distal from the first portion of the stem, wherein the first end portion comprises a stop surface that restricts motion of the second portion of the stem with respect to the first portion of the stem.

16. The prosthesis of claim 15, wherein the first portion of the stem defines a first central axis, and the second portion of the stem defines a second central axis, wherein a maximum angle between the first central axis and the second central axis is in a range of about 0 degrees to about 90 degrees.

17. The prosthesis of claim 16, wherein the first end portion of the second portion of the stem overlaps an end portion of the first portion of the stem when viewed from an axis perpendicular to the first central axis and the second central axis.

18. The prosthesis of claim 12, wherein the head is formed integrally with the first portion of the stem.

19. The prosthesis of claim 12, wherein the head is removably coupled to the first portion of the stem.

20. A prosthesis for replacement of a proximal end of a radius bone comprising: a trunnion; and a stem configured to be received in a bore of the radius bone, wherein the stem comprises a first end portion and a second end portion, wherein the first end portion is disposed between the trunnion and the second end portion, and wherein the trunnion is moveable with respect to the stem.

21. The prosthesis of claim 20, wherein the stem comprises: a main stem body; and a peg protruding from a side surface of the main stem body, wherein the trunnion comprises a pivot hinge connector protruding from a bottom surface of the trunnion, wherein the pivot hinge connector has an elongated slot configured to receive the peg of the stem, wherein the trunnion is configured to rotate about the peg of the stem.

22. The prosthesis of claim 21, wherein the trunnion comprises a stepped portion disposed at a bottom portion of the trunnion,wherein a top portion of the main stem body comprises an opening configured to receive the stepped portion of the trunnion, wherein the peg of the stem is configured to translate along the length of the elongated slot to move the stepped portion to and away from the opening of the stem.

23. The prosthesis of claim 20, further comprising a head, and wherein the trunnion is configured to receive the head.

24. The prosthesis of claim 23, wherein the head is formed integrally with the trunnion.

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